1. Technical Field
The present invention relates to a sheet post-processing apparatus for sequentially receiving sheets successively fed from an image formation apparatus of, for example, a copier, printer or the like to process in a bunch form, and performing post-processing such as end binding processing, punching processing, saddle-stitching center-folding processing and the like on the bunch of sheets.
2. Description of the Related Art
Conventionally, sheet post-processing apparatuses have been known which gather sheets discharged from an image formation apparatus such as a copier or the like, and perform end binding processing, saddle-stitching center-folding processing to make a booklet, and further, bookbinding processing by applying an adhesive to the spine of a bunch of sheets to attach a front cover. In recent sheet post-processing apparatuses, with improvements in performance of a stapler for performing binding processing, for example, such post-processing has been made possible that a bunch of several tens of sheets are bound in book form. With increases in the number of sheets to form a single bunch of sheets, when a bunch of sheets subjected to saddle-stitching processing undergo center-folding processing to be in book form, in the so-called fore-edge portion (fore-edge end) that is an open side of the bunch of sheets, center-folded inner sheet edges jut more outwardly than outer sheet edges, and the problem arises that the appearance of the booklet is not good. To solve such a problem, sheet post-processing apparatuses have been developed which have trimming means for trimming the fore-edge portion of a bunch of sheets subjected to center-folding processing.
As a first conventional example of such a sheet post-processing apparatus provided with the trimming means, Patent Document 1 discloses a paper processing apparatus having a configuration where a stapling processing section for processing sequentially fed sheets in a bunch form to bind a bunch of sheet is disposed in the center portion of the apparatus, and under the stapling processing section are disposed a saddle-stitching unit for binding the center portion of the paper bunch, and a center-folding unit 50 for folding the paper bunch along the bound portion. Herein, it is configured that a cutter unit 60 for cutting an edge portion of the bound paper bunch is provided in the downstream stage of the center-folding unit 50, and that a press lever 65 included in the cutter unit 60 holds the paper bunch when the paper is cut.
Further, as a second conventional example of the sheet post-processing apparatus provided with the trimming means, Patent Document 2 discloses a paper processing apparatus in which disposed are a paper carry-in entrance 55 situated in one side face, a saddle-stitching paper discharge outlet 56 disposed in the other side face that is the side opposite to the paper carry-in entrance 55, a saddle-stitching compile tray 21 extending from above the one side face side to below the other side face side, while aligning and holding a plurality of sheets fed from the paper carry-in entrance 55, and a saddle-stitching stapler 24 for binding a predetermined portion of the paper bunch held and aligned, and provided further are a folding knife 25 for folding the bound paper bunch, a rotary cutter unit 30 provided above the saddle-stitching compile tray 21 in the vertical direction to cut the folded paper using a blade traveling in the horizontal direction, and a booklet tray 51 to load the paper which is cut by the rotary cutter unit 30 and discharged from the saddle-stitching paper discharge outlet 56.
Furthermore, as a third conventional example of the sheet post-processing apparatus provided with the trimming means, Patent Document 3 discloses a post-processing apparatus which has a feeder for feeding a cover sheet, a carrying path for carrying the cover sheet and paper, center-folding means for making a fold in the direction perpendicular to the carrying direction of the cover sheet and paper on the path, carrying means for carrying the cover sheet and paper each with the fold made and opened on a sheet basis, loading means for loading the cover sheet and paper, saddle-stitching means having staple putting means and staple receiving means for performing saddle-stitching processing on a paper bunch formed of the cover sheet and paper on the loading means, and trimming means for trimming a fore edge of the paper bunch subjected to the saddle-stitching processing to be a book, and which has the feature that the feeder, trimming means and the saddle-stitching means are arranged in the vertical direction.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-261260    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2004-195569    [Patent Document 3] Japanese Laid-Open Patent Publication No. 2004-115237
However, in the sheet post-processing apparatus thus provided with the trimming means, since it is necessary to arrange the end binding processing means, saddle-stitching processing means, center-folding means and also the trimming means in the limited space within the apparatus frame, as in the above-mentioned first and third conventional examples, the trimming means for finally trimming a fore-edge portion of a bunch of sheets subjected to the center-folding processing is situated in the lower portion of the apparatus frame or near the sheet discharge outlet for discharging the bunch of sheets subjected to the post-processing. Further, a sheet branch portion for turning a sheet fed from the carry-in entrance to the center-folding means is disposed in the carrying path between the punch means and the end binding means. Therefore, the space becomes small which is under the end binding means and surrounded by the center-folding means and the discharge outlet.
Therefore, in such a conventional sheet post-processing apparatus, it is not possible to reserve a sufficient spade to drop trimming debris occurring in the trimming processing to store, a debris storage box is filled fully with the trimming debris, and the need arises to halt the apparatus frequently. Further, a discharge outlet for discharging a trimming-processed bunch of sheets should also be disposed in the lower portion of the apparatus, the discharge tray is filled fully with bunches of sheets in a short time, and it is necessary to halt the apparatus frequently as in removing the trimming debris.
Further, in the second conventional example as described above, such a configuration is adopted that in the apparatus frame 10 are provided, from the top, a carrying path for passing a sheet with an image formed without processing and sequentially discharging onto a first discharge tray 52, an end binding processing path for forming a bunch of sheets to perform end binding processing and collecting bunches of sheets on a second discharge tray 54, and a saddle-stitching center-folding processing path for performing saddle-stitching center-folding processing on a bunch of sheets and trimming a fore edge of the bunch of sheets which are arranged in the vertical direction. Therefore, as well as the problem that the apparatus size increases, since the trimming means for performing dangerous processing of trimming a fore edge of a bunch of sheets is disposed near the sheet discharge outlet of the apparatus frame, the risk is high for causing an accident of inflicting a wound on the finger and/or hand of an operator when the operator handles a jam and the like.
The present invention was made to solve various problems in the conventional sheet post-processing apparatus as described above, and it is an object of the invention to secure a space for sufficiently storing trimming debris, while enabling the high number of trimmed bunches of sheets to be stored as much as possible within the limited space inside the sheet post-processing apparatus, thereby reduce the frequency of halting the sheet post-processing apparatus and dramatically improve efficiency of the sheet post-processing.